SIP is an application-level protocol for creating, modifying and/or terminating multimedia sessions. SIP can be applied in areas such as establishing and terminating voice, video and/or messaging sessions over the Internet. SIP also can be used to establish video conferencing, streaming multimedia distribution, instant messaging, filter transfer and online gaming. When establishing and terminating a multimedia communication, SIP can be used to determine user locations—the locations of end user systems for the communication, user availability—the willingness of a called party to engage in the communication, and user capabilities—the media or media parameters available for the communication. SIP also can be used to perform session setup by establishing session parameters for the parties involved and to manage sessions, including transferring and terminating sessions, modifying session parameters and invoking services within sessions.
IMS is an architectural framework for delivering Internet Protocol (IP) multimedia services. In many instances, IMS has adopted SIP for session management.